⭐️SP12/SP13-Magnetism, Motor Effect And Electromagnetic Induction Flashcards Preview

Physics Gcse > ⭐️SP12/SP13-Magnetism, Motor Effect And Electromagnetic Induction > Flashcards

Flashcards in ⭐️SP12/SP13-Magnetism, Motor Effect And Electromagnetic Induction Deck (58)
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What is a permanent magnet?

A magnet that’s always magnetic


What is a magnetic field?

The space around a magnet where it can attract the materials iron, steel, nickel and colbalt


What is an induced magnet?

Where a piece of magnetic material is in a magnetic field and becomes a magnet its self and stops being a magnet when taken out


What can you use to find the shape of a magnetic field?

Using plotting compasses


Give examples where magnets are used

Electric motors, generators, loudspeakers and things like for latches am life holders


How do plotting compasses work?

The needle is a very small magnet and this points to the earths North Pole because the south is attracted to it


Why are compass needles weighted at one end?

To keep them level


What is the evidence for the earth’s magnetic field?

The behaviour of compasses


What is the earths magnetic field caused by?

Electric currents in the molten outer core made of a mixture of iron and nickel


Explain the magnetic field outside a solanoid

The field outside is weaker because fields from one side of the coil tend to cancel court fields on the other side of the coil


Explain the magnetic field inside a solenoid

The field is very strong because the individual fields add together to form a very strong field


What is an electromagnet?

A coil of wire with a current flowing through it


What happens of you put iron in an electromagnet? What does the iron become?

You make the magnetic field stronger, the iron becomes a temporary magnet because it’s only magnetic while the field from the electromagnet is affecting it


What is caused when a current flows through a wire?

A magnetic field


What does the direction of a magnetic field on a wire carrying a current depend on and what happens of this changes direction?

Depends on the direction of current and if this changes direction, so does the direction of magnetic field


What does the strength of a magnetic field around an electrical wire depend on?

The size of the current so the higher the current the stronger the field


Where is the magnetic field around a wire strongest?

Closer to the wire


What is a solanoid?

A coil of wire with a magnetic field around it


What happens when a wire is placed between two magnets?

It experiences a force as the current created a magnetic field and this interacts with the magnetic field between the magnets


When is the force a wire carrying current the greatest?
When is the force at 0?

When the wire is at right angles to the magnetic field produced by the magnets (as the wire has to be between two magnets to feel the force in the first place
0 when the wire is in the same direction as the magnetic field


What is the motor effect?

When a wire carrying a current experiences a force when placed between two magnets


What does the direction of the force in a wire carrying a current between two magnets depend on?

The direction of the magnetic field and the current


How can you use Fleming’s left hand rule?

To determine the direction if the current in the motor effect so:
The force is the thumb F
Magnetic field is the index finger B
The current is the index finger L


How do you find the force on a conductor carrying current at right angles to the magnetic field? Use units

Force (N) = magnetic field strength (N/ Am) or ( Tesla (T)) x current (A) x length (m)
F = B x I x L


What causes the rotation in electric motors?

The force on a conductor in a magnetic field


What are carbon brushes on an electric motor used for?

Make electrical contacts between the circuit and motor


Describe how an electric motor works

There is a force in each part of the wire carrying a current in the magnetic field and so using a coil with many turns of the wire increases the total force turning the coil


What does the split ring commutator do?

It ensures the force on the coil always turns it in the same direction by making the current is always flowing in the correct direction to make the coil continue to spin


What can a changing magnetic field induce?

A voltage or potential difference in a wire causing a current to flow


How can a potential difference be induced?

-changing magnetic field
-if a wire is moved in a magnetic field and this wire is often made into a coil so there is more wire in the changing magnetic field